Direct and indirect causal effects of heterozygosity on fitness-related traits in Alpine ibex
Direct and indirect causal effects of heterozygosity on fitness-related traits in Alpine ibex
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DOI：
10.1098/rspb.2014.1873
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发表时间：
2015-01-07
影响因子：
4.7
通讯作者：
von Hardenberg, Achaz
中科院分区：
文献类型：
--
作者：
Brambilla, Alice;Biebach, Iris;von Hardenberg, Achaz
杂合性-适合度相关（HFCs）是研究野生种群近交效应的有用工具，但不能区分杂合性对适合度相关性状的直接和间接影响。我们在自由放养的种群（在18世纪末遭遇严重瓶颈）中测试了雄性阿尔卑斯山野山羊（Capra ibex）中的HFCs，并使用验证性路径分析来解开杂合性和适合度相关性状之间的因果关系。我们对1985年至2009年出生的149名男性进行了氢氟碳化合物测试。我们发现，标准化的多位点杂合性（MLH），从37个微卫星位点计算，与体重和角的生长，这是已知的重要健身相关的性状，和粪便卵计数（FEC）的线虫卵，寄生虫抗性的代理。然后，使用验证性路径分析，我们能够表明，MLH对角生长的影响不是直接的，而是由体重和FEC介导的。氢氟碳化合物并不一定意味着对健康相关性状的直接遗传影响，相反，这种影响可以通过其他性状以复杂和意想不到的方式介导。
Heterozygosity-fitness correlations (HFCs) are a useful tool to investigate the effects of inbreeding in wild populations, but are not informative in distinguishing between direct and indirect effects of heterozygosity on fitness-related traits. We tested HFCs in male Alpine ibex (Capra ibex) in a free-ranging population (which suffered a severe bottleneck at the end of the eighteenth century) and used confirmatory path analysis to disentangle the causal relationships between heterozygosity and fitness-related traits. We tested HFCs in 149 male individuals born between 1985 and 2009. We found that standardized multi-locus heterozygosity (MLH), calculated from 37 microsatellite loci, was related to body mass and horn growth, which are known to be important fitness-related traits, and to faecal egg counts (FECs) of nematode eggs, a proxy of parasite resistance. Then, using confirmatory path analysis, we were able to show that the effect of MLH on horn growth was not direct but mediated by body mass and FEC. HFCs do not necessarily imply direct genetic effects on fitness-related traits, which instead can be mediated by other traits in complex and unexpected ways.